Method of rendering iron castings malleable.



NITED STATES JOHN C. BRADLEY, OF BUFFALO, NEW YORK.

METHOD OF RENDERING IRON CASTINGS MALLEABLE.

SPECIFICATION forming part of Letters Patent No. 637,369, dated November 21, 1899. Application filed August 14, 1899. Serial No. 727,236. (No specimens.)

To all whom it may concern:

Be it known that I, JOHN C. BRADLEY, a citizen of the United States, residing in Buffalo, county of Erie, and State of New York, have invented a new and useful Improvement in Methods of Rendering Iron Castings Mal- 1eable,-of which the following is a specification.

In the process of rendering iron castings malleable as ordinarily practiced the iron castings are packed in annealing pots or boxes, together with steel scale, wrought-iron borings or turnings, or other small particles of iron, which material has been treated with sal-ammoniac or to which sal-ammoniac has been added. These pots or boxes are then placed in the annealing-kiln and exposed to a high degree of heat fora suitable period of time,as the nature of the castings may require. In the cast-iron of which such castings are formed the carbon is combined with the iron, and such castings show a white fracture when broken, while in the annealed castings the percentage of carbon is less than in the original state and the carbon which remains is uncombined or in the graphitic state, so that the annealed castings show a blackish or dark-blue fracture. The material which is used for this packing-such as steel scale, wrought-iron scale, wrought-iron turningsis expensive, and its treatment with sal-ammoniac increases the expense. Furthermore, this material fuses at a comparatively low temperature and often cakes at the annealing heat to such an extent that it adheres tenaciously to the castings and pots, so that it always involves considerable labor to remove the castings from the pots and to free the annealed castings from the adhering packing material, which is particularly difficult when the castings are intricate or have recesses, cavities, or crevices. The packing material often becomes so lumpy during the annealing process that it must be pulverized before it can be used again.

The object of my invention is to overcome these difficulties and to reduce the cost of annealing such castings.

In practicing my invention I pack the iron castings in furnace-slag which is rich in iron oxid and which has been coarsely pulverized The castings or cake at the annealing heat and therefore does not adhere to the annealed castings, but remains granular and leaves the castings and the pots readily, so that the castings are removed from the pots freely and in a clean condition, unencumbered by adhering pack: ing material. This packing material reduces the percentage of the carbon in the castings very effectively and changes the remaining carbon to the graphitic state, producing annealed or malleable-iron castings of excellent quality. This packing material is a waste product of the iron furnace and is of no value. It can be made ready for use at trifling cost, as it only requires to be crushed or pulverized, and as it does not fuse or cake it remains in the proper condition for use. The

use of this packing material avoids the heavy expense attending the use of the materials heretofore used for this purpose, which expense arises both from the cost of the material and the cost of cleaning the castings and retaining the material in the tion for use.

I claim as my invention The herein-described method of annealing iron castings which consists in packing the castings in pulverized furnace-slag which is rich in iron oxid and subjecting such packed castings to the annealing heat, substantially as set forth.

Witness my hand this 8th day of August, 1899.

JOHN C. BRADLEY.

Witnesses:

JNo. J. BONNER, ELLA R. DEAN.

proper condi- 

